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108 The Botanical Gazette. [April, 

Suggestions on the classification of Metaphyta. 

CONWAY MACMILLAN. 

The sciences of botany and zoology are not yet sufficiently 
advanced, it may be, for the proposal of that system of clas- 
sification which, at once comprehensive and natural, shall 
bind together all our ontogenetic and phylogenetic discoveries 
and generalizations into a harmonious and enduring structure. 
The season of patient toil in the acquisition of new facts in 
the departments of comparative morphology and embryology 
is not yet past; and to both the zoologist and the botanist 
there is still a vast terra-incognita presenting its untried paths 
for the work of discovery and cartography. To indicate what 
seems to be a possibly fruitful line of investigation — or rather 
to suggest the continued investigation of an already indicated 
and partially explored region, from a somewhat different point 
of view than the ordinary one — is the object of this paper. 

The bald statement that there exists a great group of living 
creatures with which students of biology have long been 
familiar, but of which there is as yet no classification, no Sys- 
tema, no Tournefort or Linnaeus, and no compendium or 
monograph of any sort, borders closely on the sensational. 
From a certain point of view this is, however, a fair statement 
and one that can be defended. The groups to which reference 
is made have been studied since the time of Camerarius and 
properly understood since the days of Hofmeister. Their 
presence as organisms is nevertheless owing to the persistence 
of ancient habits of thought, largely overlooked by the stu- 
dents of to-day. The accepted classification of the plant 
kingdom into Protophyta and Metaphyta buries every vestige 
of the group, and it is only by modifying that classification 
that the lost tribes may be made to emerge from their obscur- 
ity. In the briefest manner let us examine the ascertained 
facts of progress which are considered of importance in deter- 
mining the rank of successive series of plants and animals. 
First and lowest in the scale of differentiation are those or- 
ganisms which can not be safely grouped either with the plants 
or with the animals. These are the Protista of Hseckel, the 
third kingdom. From them as a substratum the two phyla of 
plants and animals arise. In each branch of the primitive 
trunk the lower series of organisms are devoid of sex, purely 
vegetative even in their reproductive functions. These are 



l8 9 z -J On the Classification of Metaphyta. 109 

the Protophyta and the Protozoa, or if one should apply names 
to indicate the physiological character upon which the groups 
are founded, the Agamophyta or sexless plants, and the Agam- 
ozoa or sexless animals. With such transitional forms as 
Ulothrix and some of the ciliated Infusoria the two higher 
groups of organisms are introduced and we may distinguish 
the sexual plants, Gamophyta, from the sexual animals, Gam- 
ozoa. This latter branch is almost equivalent to the Meta- 
zoa, but the Gamophyta as here limited constitute but a small 
portion of the organisms which are included as Metaphyta. 
It is precisely here that the great hiatus between our classifi- 
cation of plants and animals is to be discerned. To appre- 
ciate properly the true condition of things is perhaps more 
easy if we divide the Metazoa and Metaphyta, respectively, 
into two co-ordinate groups. This is a division of organisms, 
not of species, and can be performed, I think, without violence 
to right thinking. There may be distinguished, then, in the 
plant phylum the Sporophyta and the Gamophyta, and in 
the animal phylum the Sporozoa and Gamozoa. A sporophy- 
tic or sporozoic organism might be defined briefly as one that 
develops primarily from a segmentation-cell (fertilized egg, 
parthenogetic egg or vegetatively apogamous cell) and nor- 
mally forms in turn perfect reproductive cells or spores. In 
the plant phylum this group includes a most diverse and nu- 
merous series of organisms, from the four-zoospore-plant of 
CEdogonium to the moss-capsule, the ferns, club-mosses, 
pines, cycads, and all the herbs, shrubs and trees with which 
we are familiar. In the animal phylum, however, the Sporo- 
zoa would include only a very few and relatively insignificant 
organisms, chiefly among the Ccelenterata, and doubtfully 
extending among the Tunicata; that depending upon whether 
the views of Brooks or of his critics are to be accepted con- 
cerning the homologies of the salpa-chain. 

With the division of the two branches, Metaphyta and Met- 
azoa, it becomes apparent why the coordination of plants and 
animals under any of the systems is so unproductive of the 
most valuable systematic or philosophical results. We do not 
compare, habitually, the Sporophyta with the Sporozoa, but 
with the Gamozoa, thus missing the chance of determining 
the true parallelisms and homologies, if any exist. That 
sporophytic structures may not be compared (except physi- 
ologically) with gamophytic has already been shown by 



no The Botanical Gazette. [April, 

Bower, 1 but it does not seem to be out of place to insist here 
that such structures and organisms are even less aptly com- 
pared with the Gamozoa. 

It will be recognized as of high importance to discriminate 
in the two divergent phyla of plants and animals the truly 
double and parallel composition of each of the upper series. 
And, since the structural development in the two phyla var- 
ies reciprocally, it is not possible to compare them without 
clearly perceiving the double nature of each. For in the 
Metaphyta the sexual series has undergone progressive struc- 
tural degeneration from the mosses to the highest of the Si- 
phonogama, while in the Metazoa the sexual series manifests 
increasing complexity from the lowest Ccelenterata to the 
Primates. On the other hand, in the plant phylum, sporo- 
phytic organisms from the QEdogoniae to the highest Meta- 
chlamydeae show a constantly increasing structural differentia- 
tion ; but in the animal phylum, sporozoan organisms are de- 
veloped only low down in the scale and are discontinued long 
before the higher classes are reached. I have already indi- 
cated elsewhere what may be the reason for this remarkable 
difference between the two kingdoms 2 , and it will suffice to 
suggest that the relatively great immobility of gamete-pro- 
ducing, that is sexual, plants is the primary cause of their 
defeat in the struggle for food, sunlight and organization with 
the more capable sporophytes. This supremacy of the spor- 
ophytes is so complete that all the higher gamophytic plants 
have been forced into a most abject condition of parasitism 
upon the sporophytic structures of their own species. 

The great mass of the species grouped in the Metaphyta 
are, therefore, persistently and strongly dimorphic, and it is 
this dimorphism which distinguishes the plant from the ani- 
mal phylum. The essential diagnostic character of the 
Metaphyta might be described, indeed, as sharply defined 
specific dimorphism. While the higher animals may, for each 
species, be separated into two groups of organisms differing 
only in sex, the higher plants may, for each species, be di- 
vided into perhaps four groups or organisms, viz., the pollen- 
bearing, the pistil-bearing, the male (pollen-tube) and the 
female (embryo-sac contents). This conception of the plant 

1 Bower: Antithetic and Homologous Alternation ; Ann. of Bot. IV, 347-370, 
1890. 

2 MacMillan: Amer. Nat. XXV, 22—25, 1891. 



1892.] On the Classification of Metaphyta. 1 1 1 

species is of course rendered difficult by the as yet uneradi- 
cated error of considering pollen-tube and embryo-sac con- 
tents in the light of organs belonging to the sporophytic 
forms of the species. I have had occasion before, in these 
pages, s to call attention to the wellnigh hopeless confusion 
of botanical terminology in this region of the science. When 
Goebel speaks of the fertilized macrospore of Pilularia being 
attached to the ground by its prothallial rhizoids 4 , or when 
Muller entitles a work "The Fertilization of Flowers," in 
which fertilization is not even mentioned, it serves to illus- 
trate how deeply rooted is the fault of nomenclature which 
perpetuates the ancient errors of Camerarius, Linnaeus, 
Sprengel and Erasmus Darwin. 

It is clear that there must still be much study before bot- 
anists can hope to define their species correctly, to say noth- 
ing of grouping them in an enlightened manner. The eman- 
cipated zoologists of the day are accustomed, with an air not 
unfamiliar, to deprecate the attention bestowed upon classifi- 
cation and systematic work by the botanists. They do not, 
perhaps, discern that in a way the problems of the botanist 
are two-fold as complex as their own, just as the organisms 
with which the botanist has to do are doubly complicated. 
Up to this time so little material has been examined that 
there are very few species of Gamophyta accurately described. 
It is inconceivable that there should not exist differences be- 
tween the male plants of Salix and Populus, for example, in 
some way related to the differences between the sporophytes. 
What these differences are is a task for future investigation. 
It may be many years before the Genera Plantarum or the 
Histoire des Plantes of the higher Gamophyta is written; 
but such a work is imperative before it can be pretended that 
we are in a position to fitly describe or classify the plant phy- 
lum in a final manner. 

The evolution of sporophytic structures in the plant king- 
dom is so considerable that certain divisions should be noted 
in their development if they are to be set off against the far 
less important and less highly evolved group of the Sporozoa. 
Otherwise a wrong impression will be given in the compari- 
son. With this in view it may be advisable to recognize in 



3 Bot. Gazette, xvi, 178, 1891. 

4 Goebel: Outlines of Classification and Special Morphology, Eng. tran., 
243- 



112 



The Botanical Gazette. 



[April, 



both the Sporophyta and the Gamophyta three fairly well- 
marked physiological divisions : first, the lowest Sporophyta 
are included in the gametophytic body and are therefore 
parasitic upon the sexual plant, e. g. , CEdogonium, Chara, 
Riccia. Second, the higher forms are self-supporting and do 
not nurse the gametophytes, e. g. , the higher mosses, the 
lower fernworts and club-mosses. Third, the highest forms 
act as host-plants for dependent, symbiotic gametophytes and 

METAPHYTA 




lo^>^ 



are so specialized, e. g. , the seed-plants and the higher fern- 
worts and club-mosses. These groups might be named 
respectively the Protosporophyta, Eusporophyta, and Meta- 
sporophyta, in order to facilitate reference without paraphras- 
ing. Similarly, the lowest Gamophyta do not furnish nutriment 
for sporophytic structures of their own species, e. g. , Ulo- 



1892.] Fungi of Wild and Cultivated Plants. 113 

thrix, Fucus, Peronospora. The higher support dependent 
sporophytes, e. g. , CEdogonium, Marchantia, Sphagnum. 
The highest are symbiotically parasitic upon sporophytic 
structures of their own species, e. g. , the Isoetinea?, Sela- 
ginelleae and Siphonogama. These might be named respect- 
ively the Protogamophyta, Eugamophyta, and Metagamo- 
phyta. It is this last division that constitutes the principal 
part of the unexplored region. The accompanying diagram 
indicates the grouping of living things here suggested. 
University of Minnesota, Minneapolis. 



Some fungi common to wild and cultivated plants. 

BYRON D. HALSTED. 

Reference is here made to the relation of the fungous par- 
asites of wild plants, including weeds, to our crops whether 
of fruit, grains, or vegetables. This deleterious influence can 
best be brought out by taking up some of the worst fungous 
enemies to crops and showing the range of these parasites 
upon the surrounding wild plants. 

Starting with the garden vegetables it is easy to find illus- 
trations on every hand. Thus the lettuce mildew, Bremia 
Lactuca Reg. is found up to date upon no less than forty-one 
species of plants belonging to the same family as lettuce and 
closely related to it. Many of these hosts for the mildew are 
common garden weeds and others inhabit the uncultivated 
ground. 

The celery rust, Cercospora Apii Fr. now so destructive 
with truckers, is common to the carrot and parsnip also, and as 
the wild form of these abound without stint in many locali- 
ties we need not wonder that the garden plants are partially 
destroyed by this pest. 

There is a mildew of the spinach, Peronospora effusa Gr. 
that flourishes upon the pigweeds generally, there being no 
less than ten of these weeds that are thus infested and furnish 
a propagating place for the mildew of their patrician cousin 
grown on a salad plant. 

The bean rust, Uromyces appendiculatus (P.) is one among a 
conspicuously destructive group of fungi that makes its home 
upon several species of wild beans.